Establishing user needs for a stability assessment tool to guide wheelchair prescription.

PURPOSE: The WheelSense project aims to develop a system for assessing the stability and performance of wheelchairs through a user-centred design process. This study sought to capture user needs and define the specification for the system. METHOD: A mixed methods approach was adopted. An online survey was completed by 98 participants working in wheelchair provision. The results were built upon through 10 semi-structured interviews and one focus group (n = 5) with professionals working in wheelchair provision in three NHS Trusts in the UK. RESULTS: The results provided a picture of the current UK practice in stability testing. Issues with the reliability and usefulness of the existing methods used to assess the stability and performance of wheelchairs were highlighted. Requirements for a new system were ascertained. These included improved accuracy of tipping angles, features to support record keeping, improved client/carer education support and ability to model or predict client-wheelchair system performance in different configurations. CONCLUSIONS: The paper concludes that there is a need for improved tools to determine the stability of the client-wheelchair system and support the prescription process, to ensure client safety and optimum equipment performance. A list of requirements has been produced to guide the future development of WheelSense. Implications for Rehabilitation The results of this survey and interview-based study present a picture of wheelchair stability testing practices in the UK, and highlight the need for new, more informative methods for guiding wheelchair prescription. The requirements for the design of a new system, or further development of existing tools to support the stability testing and prescription of wheelchairs have been established.

The development and testing of a system for wheelchair stability measurement.

Wheelchair stability has an impact on safety as well as wheelchair performance, propulsion and manoeuvrability. Wheelchair stability is affected by the addition of life-supporting heavy equipment, e.g. ventilators and oxygen cylinders, as well as the characteristics of the user e.g. limb amputations, obesity. The aim of the research described here was to develop and test a stability assessment system that would guide and support the adjustment of wheelchairs to individual needs, characteristics and lifestyles. The resulting system provides assessment of centre of gravity and wheelchair stability and calculates the wheelchair tipping angles. The system consists of a force platform that senses the weight distribution of the wheelchair and calculates the centres of the contact points of the wheels and the distances between them. The measurement data are transferred via a WiFi connection to a portable tablet computer where wheelchair stability parameters are calculated. A touchscreen GUI provides visualization of the stability results and navigation through the measurement modes. The developed new concept has been evaluated through technical laboratory-based testing to determine the validity of the data collected. Initial testing has been undertaken within the clinical setting in 3 large hospitals in the UK. Initial results suggest that Wheelsense® provides a valuable tool to support clinical judgement.

The effect of seat shape on the risk of pressure ulcers using discomfort and interface pressure measurements.

BACKGROUND: It is clinically known that shape is important when selecting or designing a wheelchair support surface for the prevention of pressure ulcers (a £ 2 billion annual cost to the National Health Service, UK); however, the effect of different levels of shape contouring has not been adequately studied. OBJECTIVES: To investigate the effect of seat shape on the risk of pressure ulcers using discomfort and interface pressure measurements. STUDY DESIGN: Randomised, repeated trial. METHODS: Thirty able-bodied participants sat with restricted movement for 30 min in three sessions to evaluate two cushion shapes against a flat baseline surface. Visual Analog Scaling and pressure mapping were used to measure surrogates for pressure ulcer risk, discomfort and interface pressures, respectively. RESULTS: Linear regression revealed a reduction in discomfort (p < 0.05) on the custom contoured shapes. Interface pressures measured were also lower (p < 0.05) on the custom contoured shapes, and a negative Pearson's correlation (p < 0.05) indicated an association between smaller hip widths and increased discomfort for the commercially shaped cushion. CONCLUSIONS: The results of this study confirm that custom contoured shapes were effective at reducing pressure ulcer surrogate measures in the participants of this study and therefore suggests that the contribution of a cushion's three-dimensional contours on pressure ulcer risk should be further researched. CLINICAL RELEVANCE: The measurement of seat shape, discomfort and interface pressure in surrogate participants can help inform the design of wheelchair seating for individuals who are insensate or otherwise at risk of developing pressure ulcers. This knowledge can now be implemented using modern three-dimensional shape acquisition, analysis and fabrication technologies.

Evaluation of the Force Sensing Application pressure mapping system.

Pressure mapping techniques are used in wheelchair and seating services to assess posture and assist in the prevention and treatment of pressure ulcers. The Force Sensitive Application (FSA) pressure mapping systems in Wales have a high clinical use and frequent calibration is required. This project aimed to assess the performance of the systems and develop a calibration strategy. Testing of the systems was spilt into three stages. The pilot stage compared different calibration techniques (manual, automated and with new software) to determine the optimal calibration frequency. The second stage, longer term, was like the pilot stage with the best calibration method tested over 10 weeks. The third test was a simple before-and-after calibration test, conducted to determine the effect of calibration. It was concluded that the calibration process is essential to maintain the reliability of the mats and it was decided that the systems in Wales should be calibrated every 2 months to provide a more consistent output.